A. Field of the Invention
This invention relates to seals, and more particularly to annular seals for use with well tools which are run in well tubings.
B. Prior Art
Conventionally two types of seals are used on well tools run in a tubing; a V-type or chevron seal and an O-ring seal. Both of these seals have several undesirable characteristics.
The chevron seal requires excessive longitudinal space along the tool and must be physically displaced outwardly into sealing position. The requirements make this type of seal objectionable for small tools where tolerances are close and space for a seal is at a premium. In addition, it is difficult to energize a chevron or V-type seal into a sealing position with a low pressure differential across the seal.
O-rings seals do not have the disadvantages of chevron, V-type seals because an O-ring seal requires little space and will move into a sealing position at a low pressure differential. However, when a tool is being run in a tubing, O-ring seals on the tool tend to wash off. When the tool reaches its final position where it is to be sealed, there is no way of ascertaining whether or not the seal ring is still in position, and the tool can only be set in the hope that there will be an effective seal.